In the past decade, stretch electronics with a wide variety of functionality such as biological sensors, solar cells, polymer light-emitting devices, transistors, active matrix displays and photo-detectors have been demonstrated. While there has been progress on power sources with similar mechanical properties, there is still a significant gap. Previously supercapacitors based on single-wall nanotubes (SWNT) deposited on polydimethyl siloxane (PDMS), carbon nanotubes (CNTs) embedded in fabric and conducting polymer on compliant substrates have been demonstrated, but these devices are suited to short term energy storage and cannot be used to power stand-alone devices.
A conventional battery has two non-compliant conductors as the current collector, anode and cathode electrodes, a separator in between the electrodes to prevent electronic contact and electrolyte to provide ionic connection. The anodes and cathodes are typically a mix of electrochemically active particles mixed with a conductive material (e.g. carbon) and a polymeric/cellulose binder. These electrodes are brittle composites and have limited flexibility. Degradations in capacity during fatigue tests are generally due to formation of cracks and loss in electrical contact within the electrode during flexing.
Flexible devices (e.g. wearable devices) require a power source with a similar form factor. For example, U.S. Publication 20120276434 (Gaikwad) teaches a flexible matter formed by embedding an electroactive material inside a nylon/metal mesh. This approach provides a flexible electrode. The content of U.S. Publication 20120276434 is hereby incorporated by reference in its entirety.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.